Anti-ADAM12 agents are provided such as anti-ADAM12 antibodies (Abs), antigen-binding Ab fragments, multi-specific Abs and antigen-binding Ab fragments, antibody-drug conjugates (ADCs), and chimeric antigen receptors (CARs). Also, nucleic acid sequences and vectors are provided encoding, cells and pharmaceutical compositions comprising such anti-ADAM12 agents and methods for expanding such cells. Methods of treating, preventing, or diagnosing a disease such as cancer and methods of stimulating an immune response using such materials are also provided.